Method and apparatus for delaying electrical impulses



May 24, 1938. J, P; SMITH METHOD AND APPARATUS Fon DLAYING ELECTRICALIMPULsEs Filed Jan. 28, 1936 2 Sheets-Sheet l *Mullig- III INVENTOFIJqhn R Smith WM m N H 0 T T H May 24, 1938.

J. P. SMITH METHOD vAND APPARATUS FOR DELAYING ELECTRICAL IMPULSES FiledJan. 28, 1936 2 Sheets-Sheet 2 [ijs INVEN'T'GR JohnR Smith,

HT'T'OHNEY Patented May 2.4, 1938 PATENT OFFICE.f

METHOD AND APPARATUS FDR DELAYIN ELECTRICAL IMPULSES .101m r. smith,Erima, N. J., minor to Radio Corporation of America, a corporation ofDela- WIN Application January 2s, 193s, serial-No. 61,133

GClaims.

them occur in the proper time relation with respect to other voltageimpulses. In the said application I described and claimed one method ofdelaying rectangular electrical impulses without resorting to the use ofthe usual delay networks comprising sections of inductance coils andcapacitors.

An object ofthe present invention is to provide an improved method ofand means for delaying rectangular electrical impulses Withoutemployinga' delay network of the above-mentioned type.

A further object of my invention is to provide an improved method of andmeans for delaying a rectangular electrical impulse without impairingits wave form. I

A still further object of my invention is to provide an improved methodof and means for both narrowing and delaying a rectangular electricalimpulse. l

In practicing my invention a rectangular voltage impulse is produced byany suitable generator and supplied to two separate circuits orchannels.

In one of Ithese channels the impulse is narrowed to a width which isequal to the amount of delay desired. The impulses appearing in theoutput circuits of the two channels are added in a common circuit, theimpulse from one channel being of a polarity opposite to that of theimpulse from the 'other channel. The resulting impulse is then` passedthrough a clipping tube to remove the undesired part of the impulsewhereby the desired delayed and narrowed impulse is obtained.

Other objects, features and advantages of my invention will appear fromthe following description taken in connection with the accompanyingdrawings, in which Figure 1 is a circuit diagram of one embodiment of myinvention, and l Fig. 2 is a group of curves which are referred `to inexplaining the invention.

Referring to Fig. 1, my invention is shown applied to a synchronizingimpulse generator of the character described in my above-mentioned ap-56 plication. -As indicated in Fig. 1, a 60 cycle vertical synchronizingimpulse 5 may be supplied from a source comprising a frequency divider,indicated at I, which obtains comparatively high frequency impulses froma multivibrator or other electric discharge tube oscillator (not shown).The voltage impulse is supplied through an amplifler tube 2 to twosignal channels 3 and 4; the channel 3 including two amplifier tubes 6and l connected in cascade whereby the amplified impulse appears in theoutput circuit of the amplifier tube 1 with a positive polarity, asindicated at 3. The polarities of the impulses appearing in the platecircuits of tubes 2 and 6 are shown by the curves IIJ and I5,respectively.

The channel 4 includes three amplifier tubes II, I2 and I3 connected incascade. The input circuit of the amplifier tube II includes a couplingcondenser Il having very small capacity and a grid resistor I6 of fairlylow resistance whereby the condenser I4 and grid resistor I6 act as adifferentiating circuit for narrowing the voltage impulse suppliedthereto. The character of the signal applied to the grid of the tube IIis indicated at i1.

The grid of the tube I i is maintained at such a negative bias by meansof the grid leak biasing` provided by the condenser I4 and resistor I6that the signal applied to this grid is clipped at the level indicatedon the drawings. The resulting impulse which appears in the platecircuit of the tube Il is indicated at I8. This impulse is clipped atthe level indicated on the drawings by the amplier tube I2, this tubealso being suitably biased by means of grid leak biasing. The signalappearing in the output circuit of the tube i2 is a narrowed rectangularimpulse, as indicated at I9. This impulse is passed through the thirdamplifier tube i3 to reverse its polarity as shown at 2i.

It will vbe understood that by clipping a signal or impulse is meantremoving an undesired portion thereof, as by so biasing a tube that onlythe more positive and desired portion of the signal can be passedtherethrough, or as by saturating off the undesired portion in a vacuumtube driven beyond plate current saturation.

The plate circuit of the tube I3 is common to the plate circuit of thetube 1 in the channel 3 whereby the narrowed negative impulse 2| isadded to the wide positive impulse 8 to produce a signal of thecharacter indicated at 22.

The signal 22 is then clipped at the level indicated on the drawings bythe last'l tube 23 in the channel 3 and the resulting delayed and nar--this tube. In the circuit illustrated, the grid o! the tube 2l ismaintained at the desired negative bias by means o! grid leak biasing.It will be understood that the grids of the several clipping tubes maybe negatively biased in any other suitable way, as by means of self-biasresistors or biasing batteries.

The manner in which the rectangular impulse is delayed may be betterunderstood by referring to the curves in Fig. 2. In Figs. 1 and 2, likecurves .are indicated by the same reference numerals. It will beapparent that since the narrowed impulse 2| starts at the same time asthe wider impulse I, the amount of delay depends entirely upon the widthof the narrowed impulse. 'Ihis is made clear by the curve 22. If moredelay is desired, the narrow impulse 2| from the channel 4 is madesomewhat wider.

In the event that it is desired to narrow the impulse still furtherafter the desired delay has been determined, the input circuit of theampliiler tube 8 in the rst channel may be designed to act as adifferentiating network to narrow the impulse a desired amount, asdescribed in connection with the channel 4. In that case, the tubes 6and l will be adjusted to clip the impulse supplied thereto in the samemanner as the ampliiier tubes il and I2 in the channel l.

From the foregoing description it will be apparent that by employing myinvention a rectangular voltage wave may be delayed any amount up to thewidth of the impulse itself, without distorting the wave-shape oi theimpulse. In other words, if a rectangular impulse is put into thecircuit, the output of the circuit is also a rectangular impulse, andnotan impulse having sloping sides and rounded corners.

It will be understood that in the claims the expressions last occurringportion of said wave,

narrowed wave", composite wave having a delayed wave portion", andsimilar expressions have reference to the appearance of the wave on acathode ray tube oscillograph. On such an oscillograph, the wave appearsat various points in the circuit as illustrated in Fig. 2 where theabscissa for each curve is a time axis. Obviously, a wave of shortduration looks narrow" and may be described as a narrow wave. Theportion of a wave which actuallyy is traced last on the viewing screenby the cathode ray is the "last occurring portion" as compared with theportion of thel wave traced earlier. Likewise, the last traced portionof a composite wave such as shown by curve 22 is referred to as adelayed wave portion.

Various modifications may be made in my invention without departing fromthe spirit and scope thereofand I desire, therefore, that only suchlimitations shall be imposed thereon as are necessitated by the priorart and are set forth in the appended claims.

I claim as my invention:

1. Apparatus for delaying an electrical wave, said apparatus comprisingmeans for removing the last occurring portion of said wave to produce anarrowed wave, and means for adding said first wave and said narrowedwave in polarity opposition whereby a composite wave having a delayedwave portion is produced.

2. Apparatus according to claim 1 characterized in that means isprovided for separating said delayed portion from the remainder of saidcomposite wave.

3. In combination, means for producing a rectangular electrical impulse,means for producing a second rectangular electrical impulse which isnarrower than said ilrst impulse and which starts at the same time assaid rst impulise, means for adding said two impulses in polarityopposition whereby a resulting signal having a delayed portion portionis produced, and means for supplying only the delayed portion of theresulting signal to an output circuit.

4. A circuit for delaying a comparatively wide rectangular electricalimpulse, said circuit comprising a. channel which includes means fornarrowing said impulse while keeping its starting time unchanged, meansfor passing said wide impulse through a second channel, means for addlngthe outputs of said channels in polarity opposition, and means forclipping oif the portion of the resulting signal which represents saidnarrowed impulse and supplying the remaining portion of said resultingsignal to an output circuit.

5. The method of delaying an electrical wave which comprises removingthe last occurring portion of said wave to produce a narrowed wave,combining said rst wave and said narrowed wave in polarity oppositionwhereby a composite wave having a delayed wave portion is produced, andclipping off the undesired portion of said composite wave.

6. The method of delaying a rectangular electrical impulse whichcomprises passing said impulse through two channels, narrowing saidimpulse in one of said channels, said narrowing being done byeliminating the last occurring portion of said impulse whereby thestarting time of the impulse is not changed, adding the outputs of saidtwo channels in reverse polarity relation, and clipping off that portionof the resulting impulse which represents said narrowed impulse wherebythe remaining portion is a delayed rectangular impulse.

JOHN P. SMITH.

